Gamma prime precipitation modeling and strength responses in powder metallurgy superalloys

Mao, Jian

doi:10.33915/etd.1632

Cited by 5 publications

(4 citation statements)

References 19 publications

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“…12 is the γ′ phase distribution under 1200ºC and 30min solution annealing and water cooling. The result indicates that even water cooling can not prohibits γ′ phase precipitating in GH720Li (U720Li) during its cooling process, which is in agreement with the report by Jian Mao, Kehn Min Chang [6] etc. This reveals two parts of important information related to hot working process for GH720Li alloy.…”

Section: Primary γ′supporting

confidence: 91%

“…The chemical composition of this alloy is related to that of GH720 (UDIMET 720) from which it is derived, but differs from it with respect to the chromium, carbon and boron levels. Till now, a lot of studies [1][2][3][4][5][6] have been done for GH720Li alloy including the solutioning and precipitating of γ prime phase, the ingot to billet conversion process control, the heat treatment schedule optimizing, the mechanical behavior under service conditions, etc. However, the microstructure of GH720Li consists of primary, secondary and tertiary γ′ due to its special heat treatment schedule.…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Primary γ′ Distribution on Grain Growth Behavior of GH720Li Alloy

Zhang

Dong

et al. 2010

Superalloy 718 and Derivatives

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In this paper, a series of hot compression tests were carried out under different hot deformation parameters, covering the temperature range of 1000ºC to 1170ºC, strain rate range of 0.01s -1 to 1s -1 and compression reduction of 30%, 50%, and 70%. After that, all specimens were heat treated under the standard heat treatment schedule of GH720Li to investigate its hot deformation characteristics, especially the grain growth behaviors. The further OM and SEM observations were adopted to investigate the interaction mechanism of the primary γ′ distribution and grain growth for GH720Li alloy. The results show that for GH720Li alloy, when hot deformed below γ′ solvus, the banded or bi-model structure always occurs; while hot deformed near or over γ′ solvus, the uniform grain size distribution can be obtained. Further microstructure analysis shows that the bi-model or banded grain size distribution in GH720Li alloy is mainly due to the nonuniform re-dissolving of primary γ′ during heating process; while the uniformity of primary γ′ phase is determined by the uniformity of elements in this alloy. In other word, the homogenizing process for ingot is the key reason for later grain size control.

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Section: Primary γ′supporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

The Effect of Primary γ′ Distribution on Grain Growth Behavior of GH720Li Alloy

Zhang

Dong

et al. 2010

Superalloy 718 and Derivatives

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“…As documented in numerous studies, the creep behavior is closely related to the morphology and size of the precipitates and greatly impacts the mechanical properties [1,[13][14][15][16][17]. Indeed, the optimization of the requisite properties is achieved by a combination of grain size control, distribution of minority phases such as carbides and borides and most importantly a multisized distribution of γ phases.…”

Section: Introductionmentioning

confidence: 99%

Influence and Sensitivity of Temperature and Microstructure on the Fluctuation of Creep Properties in Ni-Base Superalloy

et al. 2020

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In this work, the sensitivity zone of microstructure and temperature for precipitation-strengthened nickel-based superalloys, used for turbine applications in aero-engines, has been firstly established. Heat treatment experiments with different solution temperatures were carried out. The microstructure evolution and creep residual strain sensitivity, low cycle fatigue properties, and tensile properties are analyzed, and the essential reason for the fluctuation of the mechanical properties of nickel-based superalloys was revealed. The main results obtained are as follows: following subsolvus solution heat treatment with a temperature of 1020 °C, samples have a high primary γ′I phase content, which is beneficial to low creep residual strain. Above the supersolvus solution temperature of 1040 °C, the creep residual strain value and low cycle fatigue performance fluctuate significantly. The essential reason for the dramatic fluctuation of performance is the presence of γ′ phases in different sizes and quantities, especially following the solution heat treatment in the temperature-sensitive zone of the γ′I phase, which is likely to cause huge fluctuations in the microstructure of tertiary γ′III phases. A zone of particular sensitivity in terms of temperature and microstructure for the γ′I phase is proposed. The range of suitable solution temperatures are discussed. In order to maintain stable mechanical properties without large fluctuations, the influence of the sensitivity within this temperature and microstructure zone on the γ′ phase should be considered.

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“…However, because of the lower γ′ content and larger grain size as compared to Rene95, the mechanical strength of Rene88DT needs further improvement. [2] Laser rapid forming (LRF) is introduced as a novel solid freeform fabrication process. In LRF, by moving the laser beam or Computer Numerical controlled working table to trace out the sliced model of a component, the solid component is formed layer by layer without die.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Heat Treatment on the Microstructure and Mechanical Properties of Laser Rapid Forming Ni-Based Alloy Rene88DT

Chen

Zhao

et al. 2007

MSF

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Laser rapid forming (LRF) is introduced as a novel fabrication process for Ni-based superalloy Rene88DT. The effect of heat treatment parameters of quenching rate and aging time on size and distribution of γ′ precipitation was investigated. The heat treatment parameters were first determined by DSC, and then optimized based on the examination of the microstructure and mechanical properties of heat treated LRF Rene88DT. The experimental results show that, the precipitation of γ′ is inhomogeneously distributed as a result of uneven heat-cycle during LRF in as-deposited Rene88DT, resulting in low mechanical properties. After being heat treated at 1165°C, 2h/AC + 760°C,28h/AC, γ ′ precipitation are homogeneously distributed with the size of 40~60nm, and the tensile strength of heat treated sample shows an increase of 400MPa as compared to that for as-deposited. The yield strength is close to that of the PM+HIP standard.

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Gamma prime precipitation modeling and strength responses in powder metallurgy superalloys

Cited by 5 publications

References 19 publications

The Effect of Primary γ′ Distribution on Grain Growth Behavior of GH720Li Alloy

The Effect of Primary γ′ Distribution on Grain Growth Behavior of GH720Li Alloy

Influence and Sensitivity of Temperature and Microstructure on the Fluctuation of Creep Properties in Ni-Base Superalloy

The Effect of Heat Treatment on the Microstructure and Mechanical Properties of Laser Rapid Forming Ni-Based Alloy Rene88DT

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